Machine for making honeycomb core material



Sept. 2, 1952 H. c. ENGEL ET AL 2,609,314

MACHINE FOR MAKING HONEYCOMB CORE MATERIAL Original Filed Oct. 50, 1946 4 Sheets-Sheet 1 3.14 jfi gwuonfous p 2 H. c. ENGEL ETAL 2,609,314

MACHINE FOR MAKING HONEYCOMB CORE MATERIAL Original Filed Oct. 30, 1946 4 Sheets-Sheet 2 Sept. 2, 1952 H. c. ENGEL ET AL 2,609,314

MACHINE FOR MAKING HONEYCOMB CORE MATERIAL Original Filed Oct. 30, 1946 4 Sheets-Sheet 3 i A b Sept. 2, 1952 H. c. ENGEL ET AL 2,609,314

MACHINE FOR MAKING HONEYCOMB CORE MATERIAL Original Filed Oct. 30, 1946 4'Sheets-Sheet 4 THEODORE R PHI/7m Patented Sept. 2, 1952 UNITED STATES MACHINE FOR MAKING HoNEYcoMB cons MATERIAL" Harry G. Engel, Towson, andWillard V. Trox'ell and Theodore P. Pajak, Baltimore, Md., assignors to The Glenn L. Martin Company, Middle River, Md., a corporation ofMaryland Original application October 30, 1946, Serial No. 706,672. Divided and this application January- 31, 1951, Serial N0. 208,700

.1 Our invention relates to amachine for making a honeycomb core structure from relatively thin strips of resin impregnated material, or the like. This is a division of application Serial No. $06,672.1iled Qctober 30, 1946, now abandoned.

Thepresentinvention provides an efficient machine for forming honeycomb core material in which relatively dense high-strength fabric strips are arranged to form hexagonal shaped cells in which the full strength of the walls of said cells are utilized to produce tensile and compressive strength in the direction of the cell axis by the provision of double and single ply wall formations in a structure characterized by having an extremely low specific gravity. 7

An object of our invention is to provide a machine for making honeycomb core material in which resin impregnated fabric material is fed through a heating area, drawn between forming .ri'bs carried in meshed'relationship to each other so as to shape the heated resin impregnated material and retain the material to the form into which it has been shaped for a sufjcient length of time to allow it .to set after which it is prepared for bonding, cut, assembled for bonding and curing as a continuous operation.

Another object of this invention is -to provide a continuous shaping machine capable of inexpensively producing core material in which resin inpregnated materialis shaped and formed as strips suited for bonding together at predetermined points to form-a cellular structure.

Other objects of this invention will become apparent from the following description when taken in conjunction with the accompanying drawings in whichlike numbers refer to like parts in different views of the drawings.

Figure 1 is an enlarged fragmentary sectional view of the honeycomb core structure ,of this invention showing arrangement of the walls of each cell. V

Figure 2 is an enlarged iragmentary sectional view of the strip material prior to shaping.

Figure 3 isan enlarged fragmentary sectional view of the same strip shaped ready for assembly.

Figure 4 is a fragmentary perspective of the core material showing its preferred embodiment as a stabilizer between two metal surface sheets. Figure 5 is a fragmentary perspective of the core having a modified form of cell structure. 7

Figure 6 is a top plan view of the strip shaping machine. e 1 1 Figure 7 is a sectional view of the machine on line 7-1 of Figure 6.

Figure 8 is an enlarged fragmentary sectional suitable theremosetting resin.

4 Claims. (01. 154-30) View ofthe shaping :ribs and bars showing their meshed positions.

Referring now to Figure l, we have illustrated a fragment of the core structure H) which shows the arrangement of the cell walls attained in the finished article. Core structure 10 is ccmprised of a plurality of hexagonal shaped cells I I having a pair of opposed wallsof double thickness and two pairs of opposed walls of-single thickness formed of suitable flexible material rendered formable by being impregnated with a Most satisfactory results have been obtained by theusejof fabric sheets impregnated with a phenol-formaldehyde to a resin content of about 50% by weight which has been partially cured prior to being out to the desired width for shaping. The fabric in its pre-shaped form is illustrated in Figure 2 asa flat sheet 12. This flat sheet 12 is cut into the form of a continuous strip. I 6 suited forhandling as a roll and adapted for shaping in the continuous shaping machine hereinafter described to pro vide theshaped strip l5 as shown in Figure 3, having bond areas l3 longitudinally spaced apart and positioned above and below the center line of the original sheet. The intervening areas between the bond areas l3'are shaped to form't-he sloped wall areas M as best illustrated in Figure 3. This configuration of the alternate bond areas 13 and Wall areas 14 may also bereferred to as formations representing one-half of the hexagonal shaped cell H of the finished core assembly. V

The machine of this-invention is shownby Figures 6 and 7 mounted on a heavy rigid-frame structure of conventional design having a bed plate I! extending I between upright sidewall members l8 and IQraised above theiloor level and supported by suitable channeled legs 2 arranged in pairs; Cross members 2! positioned between and welded to the legs add additional rigidity to the structure.

- Side wall members 18 and it are extended upwardly to receive a removable roller 42 adapted to position the roll 4] of strip material 16 for aligned feeding ofthe strip into the shaping mechanism. The strip shaping mechanism of the machine is comprised of a large cylinder 22 mounted transversely tothe bed plate -ll with bearings 23-and 24 carried by the. side wall/members I8 and l9.- Around the outer periphery of cylinder 22 a pluralityof shaping ribs 25 are provided in the form of gear teeth. Each rib 2 5 is formed with a flat top 72 (Figure 8) and sloping sides l3 separatedby a flat bottom land 14 equal in width to that of each top, it being intended that the geometry of each rib be that of onehalf of a hexagonal.

The flat top surfaces 72 of the ribs 25 are shaped and dimensioned so as to produce the fiat areas 26 in one side of the shaped strip I5 (Fig. 3) spaced between the bond areas l3, likewise the sloping side areas !!3 correspond to the interior of the sloped Wall areas I4 of the haped strip. The bottom land areas I4 between the ribs correspond to the bond areas I3 as formed on one side of the shaped strip I5.

A driving roller 28 is spaced from the large cylinder 22 a sufiicient distance to allow for meshed engagement of the ribs 25 with bars 35 corresponding in shape and size with ribs 25 and carried by a flexible endless conveyor 31. The driving roller 28 is secured to drive shaft 29 journaled in suitable bearings carried by the side walls with one end of the shaft extended beyond the side wall I8 to allow for drive attachment of pulley 30. Pulley 30 is adapted for belt, or like drive, through a second pulley 3| of a speed reduction drive mechanism 32 powered by an electric motor 33 supported by a bracket 34 bolted to side wall I8. Speed reduction unit 32 is preferably of a variable speed type, however, any conventional unit of the proper power output capable of being operated at a certain predetermined speed will prove satisfactory. Cross bars 35 corresponding in length and shape to ribs 25 are spaced and mounted on a nonstretchable flexible fabric endless conveyor belt 31 so as to provide for loose meshed engagement with the shaping ribs 25 carried by the large cylinder 22. Each one of the cross bars 35 is affixed to belt conveyor 31 by screw bolts 95. or like means, inserted through the belt material. The conveyor belt 31 is in turn supported and held in position by a stretchable endless supporting belt 36 formed of rubber or like material adapted for encirclement of the driving roller 28 and positioning roller 38 positioned under the large cylinder 22. The supporting belt is maintained at the proper operating tension by an adjustable idler 39 mounted back of the positioning roller to hold the cross bars 35 of the conveyor belt 31 in meshed position with shaping ribs 25 for a predetermined distance around the outer periphery of the large cylinder 22. I In this manner a shaping means is provided capable of maintaining a firm but resilient engagement between the shaping ribs of the large cylinder and the bars carried by the endless conveyer belt respectively. The shaping ribs 25 and bars 35 being maintained in fixed positionrelative to each other provide the sloped sides and flat top and bottom shaping areas in uniform engagement for a predetermined distance. The distance determined being sufficient to allow for the strip I6 of thermosetting resin impregnated fabric rendered formable by application of heat to be shaped to the contour of the shaping members and to be held to such shape until cooled sufficiently to become fixed as a continuous operation. This arrangement of a resillent'supporting belt positioned to back up the shaping cross bars 35 and thereby hold them in constant meshed relationship with the ribs 25 for the required shaping distance prevents any tendency that the endless conveyor belt 31 might otherwise have to sag away from the large cylinder 22.

For convenience of feeding, the resin impregnated strip I6 is wound into a roll 4| and placed above the shaping mechanism on roller 42 mounted between the side walls from whence the material can be readily unrolled as needed.

The strip I5 is then carried through a heating area represented by heating unit 45 (Figures 6 and 7) which may consist of an electric heating coil, a bank of lamps, or like heating means of sufiicient capacity to heat the strip to from 350 F. to 375 F. at which temperature it is rendered formable and suited for feeding between shaping ribs 25 and cross bars 35 which mesh sufiiciently to draw the strip in its heated condition therebetween and hold it to the desired shape while advancing the strip to the point where the meshed members separate, moving the strip material, which in its shaped condition is illustrated and referred to as shaped strip l5 (Figure '7), outwardly away from the meshed shaping members onto the platform of the machine. The shaped strip I5 is then in proper condition for further fabrication except for possible slight irregularities and a glaze which customarily forms on the surface of the strip due to the curing characteristics of the thermosetting resin and in those instances where an extremely close bond is desired we have found it desirable to remove said irregularities and glaze by means of a suitably mounted sanding mechanism. We are aware, however, that certain improved high strength adhesives may eliminate the need for the sanding operation. The sanding mechanism consists of a pair of endless sanding belts mounted for crosswise operation in contact with the top and bottom bond areas I3 of the shaped strip I5 as it is moved along the machine platform 64. By operation of the sanding belts crosswise of the strip I5 the fiat bond areas I3 are worked parallel to their sloped walls whereby the inherent stiffness of the walls is utilized to secure evenly sanded surfaces. The top sanding belt 46 (Figures 6 and 7) is positioned to move crosswise of strip as an endless belt in a given direction around a pair of top rollers 48 and 49 provided with suitable bearings carried by the machine side walls. The bottom sanding belt 41 is similarly mounted for movement in the opposite direction to engage the bottom side of the strip on a pair of bottom rollers 16. Power for the operation of the sander is provided by an electric motor 50 suitably mounted to provide for direct drive through a set of pinion gears I5. The bottom sanding belt 41 is driven in the opposite direction by the same motor by means of a pulley mounted on the end of the shaft of top roller 48 and a like pulley mounted on the bottom roller I6 connected by a belt 18. The sandor is enclosed in a suitable housing 52 and provided with an exhaust fan 19 driven by an electric motor 80 for conduction of the resin dust produced by the sander away from the machine through outlet 8|.

In order to provide for bonding of the strips together, it is necessary that a second coating of thermosetting resin be applied to the bond areas I3 and this is accomplished by introducing the shaped strip I5 to a suitable wetting mechanism which we have illustrated as a double acting spreader having a top spreader roll 53 and bottom spreader roll 54 mounted for contact with the moving strip to apply a solution of bond material to the areas prepared for 'bonding on both sides of the strip as it passes therebetween. A reservoir for the bonding material solution is provided by a supply tank55 mounted on the side wall I8 of the machine. Conveyance of the resin from the supply tank to the top roll 53 is provided for by a duct .56 equipped with a shutoif valve El. A supply of resin to the bottom roll 54 is provided for by a dip tray .58 arranged for partial submersion of the spreader roll in the fluid supplied thereto. Resin is conveyed from the supply; tank 55 to the dip tray 58 by a secondduct-Sil provided with a control valve 5|. Thelevel of resin in the tray may be automatically maintained at the right point by means of a float system (not shown) if desired. Dip tray as is supportedunder the bottom spreader 54 by a suitable support bracketed to the side walls such as cross member 59. Excess resin is scraped from-the top spreader roll by means. of a scraper-52,. No scraper is needed for the bottom roll as when operated under normal conditions there is no tendency of the strip to pick up excess resin. Rotation of the spreader rolls 53 and 54 is accomplished by a suitably geared electric motor 63 supported from' the platform 64 and connected to the spreader rolls by belted drive '83.

Cutting of the continuous "shaped strip I5 into suitable lengths for use is accomplished by means of a knife I55 provided with a biased cutting edge mounted on a rotatable drum 6% arranged for timed operation by an electric motor 84 (Figure 6) controlled by means of a microswitch 85. In this manner the material can be cut to any desired lengths, however, in producing honeycomb construction material it for commercial panels, a time setting suited to cut the strip to either i, 6 or 8 foot lengths would be utilized.

The cut lengths of the shaped strips I5 are in proper position as they move from the knife to be dropped into an assembly rack or box conaeoasm the quantity of .inaterial carried in. the roll may be. varied as production demands warrant. n The speed of productionmay.a1s'o be increased by increasing the amount of heat supplied to the strip I6 and by providing some form of mechanical cooling means to speed .up curing of the thermosetting resin carried by the strip after shaping. While we have avoided showing use of special cooling means for purposes of simplic- ,ity, it has been found practicable to speed up production of materialto arate of approximately forty feet per minute by use ioflsuch means. For the same'reason anyv showing of disconnecting means is omitted from the driving mechanism, it being understood, ofcourse, that in some instances it would be considered advisable to equip the machine with. a conventionalform of clutch controlled drive as well as conventional overload release controls.

Operation of themachine in the construction of cellular core material is as follows:

A continuous strip I5 of flexible thermosetting resin impregnated material cut to suitable width for passing through the .machine is rolled and placed on shaft 42. The free end of the strip I6 is passed under the heating unit 45 energized from a suitable source of electrical supply current and placed in contact with cylinder 22. The main driving motor 33 is energized from a supply line (not shown) which in turn rotates the driving roller 28 moving shaping cross bars 35 aflixed to conveyor belt 3'! into meshed 'engagement with shaping ribs 25 positioned around the outer periphery of cylinder .22. The free end -of strip I6 'is thereby drawn between the shaping members and so shaped to'their configuration, having beenren'dered formable by the heat ventionally placed at the end of the machine platform 54 supported by a table 88. The assembly rack is provided with a floor 6]. sides 68 and 59, fixed end It, and an adjustable end I I. The adjustable end II is suitably positioned by means of adjusting screws 85 mounted in an'end brace 8'! to provide for proper. placement, either by hand or by an automatic handling device (not shown), of the strips in stacked relationship so that the fiat surfaces that provide the bond areas ISof each strip will fall on the bond areas of each preceding strip to provide a series of hexagonal cells therebetween. After a suitable number ofstrips have been assembled a top plate (not shown) adapted to hold the strips in assembled position with the bond areas I3 in contact with each other is placed on top of the assemblage 89. The assembled strips are then bonded together at the bond areas by the application of suificient heat to completely cure the second coating of thermosetting resin applied to the strips by the spreader.

The assemblage 89, after cooling, represents the bonded cellular structure referred to as core I0 and is then in condition for cutting or shaping to any specific thickness required. In the economical production of core, we have found it advisable to form material to substantially the full width capacity of the shaping machine. Such an assemblage is well suited for cutting into sheets of any desired thicknesses on regular wood working equipment. Furthermore, it can be stored for further Working and sizing as the need arises.

In the operation of our improved continuous form shaping machine, it is understood that supplied by heating unit 45. The function of endless be1t,36 is not only to act as a driving medium upon which conveyor belt 3! rides but also a support and holding means to hold the shaping members in position long enough for the resin carried by the strip material to cool and fix the shape of the strip'to that of the shaping members. Having been so shaped, the strip material emerges as shaped strip I5 formed with a series of flat areas equally displaced outwardly from the center line of the original strip. Any irregularities as well'as the glazed resin sur" face formed by. the resin are removedfrom these flat areas by the sanding beltsv 46 and A! mounted and driven so asto move in opposite directions across said flat areas herein referred to and shown as bond areas I3. The shaped strip I5 is then passed between resin spreading rolls 53 and 54 which place a fresh coating of thermosetting resin on said bond areas I3 preparing them for bonding together. The strip is then cut into suitable lengths by a cutting knife 65 arranged to operate at spaced intervals. The cut sections of strip I5 are then stacked either by hand or mechanically in a receiving form with the bond areas I3 together to form an assemblage 89 of stacked strips after which the assemblage is heated to substantially 300 F. for about 15 to 20 minutes to completely cure and bondsaid strips together to form the stiif cellular core II).

Our inventionis capable of 'many modifications Within the scope of this specification and is therefore not intended to be limited to the nated fabric comprising a base frame having" side members and a work platform, a material support means positioned for delivery of the fabric strip, a heater positioned to heat the strip, a revolvable cylinder mounted transversely of the work platform having regularly spaced members shaped as half-hexagonals mounted crosswise around the outer periphery of said cylinder, an endless conveyer belt, a plurality of members shaped as half-hexagonals mounted on the conveyor belt crosswise thereto and spaced for meshed engagement with the similarly formed members of .the revolvable cylinder, a resilient drive belt positioned to carry the conveyerbelt in meshed engagement with said cylinder for a predetermined enwrapped distance, drive means connected to the drive belt for maintaining successive meshed engagement between the halfhexagonal members to progressively work, shape and fix the shape of the heated strip as a series of half-hexagonals having flat bond areas equally disposed from a median plane.

2. A machine for corrugating partially cured resinous core material comprising a frame, a heater carried by said frame, a material feed means carried by said frame for feeding a strip of phenolic resin impregnated fabric adjacent the heater, a pair of opposed corrugation forming elements arranged to receive the heated strip therebetween, each comprising a continuous series of matched half-hexagonallyshaped members arranged for meshed engagement with one another with the strip therebetween, one of said corrugation forming elements being in the form of a flexible endless belt, a resilient drive belt arranged to urge the flexible endless belt into meshed engagement with the other of said corrugation forming elements throughout a substantial portion of the peripheral length thereof whereby said strip is corrugated and held between said corrugation forming elements until the strip is cooled and fixed in shape, and drive means operatively connected to the resilient belt to move the members into successive engagement and advance the shaped strip. f

3. A machine for corrugating a strip of partially cured phenolic resin impregnated fabric material comprising a frame, a heater carried by said frame, a material feed means carried by said frame for feeding said strip of phenolic resin impregnated fabric adjacent the heater, a pair of opposed corrugation forming elements arranged to receive said heated strip therebetween, each comprising a continuous series of matched half-hexagonally shaped members ar ranged for meshed engagement with one an other with the strip therebetween, one of said corrugation forming elements being in the form of a flexible endless belt, and means for driving said opposed corrugation forming elements and for urging them into meshing relationship with one another including a resilient belt arranged to urge the flexible endless belt into meshed engagement with the other of said corrugation forming elements throughout a substantial portion of the peripheral length thereof whereby said strip is corrugated and held between said members until the strip is cooled and fixed in shape.

4. A machine for corrugating a strip of partially cured phenolic resin impregnated fabric comprising a frame, means carried by said frame for supporting said strip, a heater carried by said frame for heating said strip, strip corrugating means carried by said frame for receiving and shaping said heated strip including a revolvable cylinder having its outer wall corrugated wherein the axes of said corrugations extend axially of said cylinder, an endless conveyor belt having one side thereof corrugated, a resilient drive belt positioned to carry said conveyor belt in meshed engagement with said cylinder for a predetermined enwrapped distance, and drive means operatively connected to said resilient drive belt for maintaining successive meshed engagement between said'corrugations to progressively feed the heated'strip therethrough whereby to corrugate said strip.

HARRY C. ENGEL. WILLARD W. TROXELL. THEODORE P. PAJAK.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 785,786 Wolff Mar. 28, 1905 1,565,532 Tupper Dec. 15, 1925 2,300,760 Amigo Nov. 3, 1942 2,494,642 Case et a1 Jan. 17, 1950 2,518,164 Meyer Aug. 8, 1950 FOREIGN PATENTS Number Country Date 312,801 Great Britain June 6, 1929 

1. A MACHINE FOR FORMING CORD MATERIAL FROM A STRIP OF PARTIALLY CURED PHENOLIC RESIN IMPREGNATED FABRIC COMPRISING A BASE FRAME HAVING SIDE MEMBERS AND A WORK PLATFORM, A MATERIAL SUPPORT MEANS POSITIONED FOR DELIVERY OF THE FABRIC STRIP, A HEATER POSITIONED TO HEAT THE STRIP, A REVOLVABLE CYLINDER MOUNTED TRANSVERSELY OF THE WORK PLATFORM HAVING REGULARLY SPACED MEMBERS SHAPED AS HALF-HEXAGONALS MOUNTED CROSSWISE AROUND THE OUTER PERIPHERY OF SAID CYLINDER, AN ENDLESS CONVEYER BELT, A PLURALITY OF MEMBERS SHAPED AS HALF-HEXAGONALS MOUNTED ON THE CONVEYOR BELT CROSSWISE THERETO AND SPACED FOR MESHED ENGAGEMENT WITH THE SIMILARLY FORMED MEMBERS OF THE REVOLVABLE CYLINDER, A RESILIENT DRIVE BELT POSITIONED TO CARRY THE CONVEYER BELT IN MESHED ENGAGEMENT WITH SAID CYLINDER FOR A PREDETERMINED ENWRAPPED DISTANCE, DRIVE MEANS CONNECTED TO THE DRIVE BELT FOR MAINTAINING SUCCESSIVE MESHED ENGAGEMENT BETWEEN THE HALFHEXAGONAL MEMBERS TO PROGRESSIVELY WORK, SHAPE AND FIX THE SHAPE OF THE HEATED STRIP AS A SERIES OF HALF-HEXAGONALS HAVING FLAT BOND AREAS EQUALLY DISPOSED FROM A MEDIAN PLANE. 